463 lines
16 KiB
C++
463 lines
16 KiB
C++
//=== AMDGPUPrintfRuntimeBinding.cpp - OpenCL printf implementation -------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// \file
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//
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// The pass bind printfs to a kernel arg pointer that will be bound to a buffer
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// later by the runtime.
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//
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// This pass traverses the functions in the module and converts
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// each call to printf to a sequence of operations that
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// store the following into the printf buffer:
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// - format string (passed as a module's metadata unique ID)
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// - bitwise copies of printf arguments
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// The backend passes will need to store metadata in the kernel
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//===----------------------------------------------------------------------===//
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#include "AMDGPU.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/IR/DiagnosticInfo.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Support/DataExtractor.h"
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#include "llvm/TargetParser/Triple.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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using namespace llvm;
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#define DEBUG_TYPE "printfToRuntime"
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#define DWORD_ALIGN 4
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namespace {
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class AMDGPUPrintfRuntimeBinding final : public ModulePass {
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public:
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static char ID;
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explicit AMDGPUPrintfRuntimeBinding();
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private:
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bool runOnModule(Module &M) override;
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};
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class AMDGPUPrintfRuntimeBindingImpl {
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public:
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AMDGPUPrintfRuntimeBindingImpl() {}
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bool run(Module &M);
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private:
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void getConversionSpecifiers(SmallVectorImpl<char> &OpConvSpecifiers,
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StringRef fmt, size_t num_ops) const;
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bool lowerPrintfForGpu(Module &M);
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const DataLayout *TD;
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SmallVector<CallInst *, 32> Printfs;
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};
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} // namespace
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char AMDGPUPrintfRuntimeBinding::ID = 0;
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INITIALIZE_PASS_BEGIN(AMDGPUPrintfRuntimeBinding,
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"amdgpu-printf-runtime-binding", "AMDGPU Printf lowering",
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false, false)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
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INITIALIZE_PASS_END(AMDGPUPrintfRuntimeBinding, "amdgpu-printf-runtime-binding",
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"AMDGPU Printf lowering", false, false)
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char &llvm::AMDGPUPrintfRuntimeBindingID = AMDGPUPrintfRuntimeBinding::ID;
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namespace llvm {
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ModulePass *createAMDGPUPrintfRuntimeBinding() {
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return new AMDGPUPrintfRuntimeBinding();
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}
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} // namespace llvm
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AMDGPUPrintfRuntimeBinding::AMDGPUPrintfRuntimeBinding() : ModulePass(ID) {
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initializeAMDGPUPrintfRuntimeBindingPass(*PassRegistry::getPassRegistry());
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}
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void AMDGPUPrintfRuntimeBindingImpl::getConversionSpecifiers(
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SmallVectorImpl<char> &OpConvSpecifiers, StringRef Fmt,
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size_t NumOps) const {
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// not all format characters are collected.
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// At this time the format characters of interest
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// are %p and %s, which use to know if we
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// are either storing a literal string or a
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// pointer to the printf buffer.
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static const char ConvSpecifiers[] = "cdieEfgGaosuxXp";
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size_t CurFmtSpecifierIdx = 0;
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size_t PrevFmtSpecifierIdx = 0;
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while ((CurFmtSpecifierIdx = Fmt.find_first_of(
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ConvSpecifiers, CurFmtSpecifierIdx)) != StringRef::npos) {
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bool ArgDump = false;
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StringRef CurFmt = Fmt.substr(PrevFmtSpecifierIdx,
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CurFmtSpecifierIdx - PrevFmtSpecifierIdx);
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size_t pTag = CurFmt.find_last_of('%');
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if (pTag != StringRef::npos) {
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ArgDump = true;
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while (pTag && CurFmt[--pTag] == '%') {
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ArgDump = !ArgDump;
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}
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}
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if (ArgDump)
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OpConvSpecifiers.push_back(Fmt[CurFmtSpecifierIdx]);
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PrevFmtSpecifierIdx = ++CurFmtSpecifierIdx;
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}
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}
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static bool shouldPrintAsStr(char Specifier, Type *OpType) {
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return Specifier == 's' && isa<PointerType>(OpType);
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}
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constexpr StringLiteral NonLiteralStr("???");
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static_assert(NonLiteralStr.size() == 3);
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static StringRef getAsConstantStr(Value *V) {
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StringRef S;
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if (!getConstantStringInfo(V, S))
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S = NonLiteralStr;
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return S;
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}
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static void diagnoseInvalidFormatString(const CallBase *CI) {
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DiagnosticInfoUnsupported UnsupportedFormatStr(
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*CI->getParent()->getParent(),
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"printf format string must be a trivially resolved constant string "
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"global variable",
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CI->getDebugLoc());
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CI->getContext().diagnose(UnsupportedFormatStr);
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}
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bool AMDGPUPrintfRuntimeBindingImpl::lowerPrintfForGpu(Module &M) {
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LLVMContext &Ctx = M.getContext();
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IRBuilder<> Builder(Ctx);
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Type *I32Ty = Type::getInt32Ty(Ctx);
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// Instead of creating global variables, the printf format strings are
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// extracted and passed as metadata. This avoids polluting llvm's symbol
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// tables in this module. Metadata is going to be extracted by the backend
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// passes and inserted into the OpenCL binary as appropriate.
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NamedMDNode *metaD = M.getOrInsertNamedMetadata("llvm.printf.fmts");
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unsigned UniqID = metaD->getNumOperands();
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for (auto *CI : Printfs) {
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unsigned NumOps = CI->arg_size();
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SmallString<16> OpConvSpecifiers;
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Value *Op = CI->getArgOperand(0);
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StringRef FormatStr;
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if (!getConstantStringInfo(Op, FormatStr)) {
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Value *Stripped = Op->stripPointerCasts();
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if (!isa<UndefValue>(Stripped) && !isa<ConstantPointerNull>(Stripped))
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diagnoseInvalidFormatString(CI);
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continue;
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}
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// We need this call to ascertain that we are printing a string or a
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// pointer. It takes out the specifiers and fills up the first arg.
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getConversionSpecifiers(OpConvSpecifiers, FormatStr, NumOps - 1);
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// Add metadata for the string
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std::string AStreamHolder;
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raw_string_ostream Sizes(AStreamHolder);
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int Sum = DWORD_ALIGN;
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Sizes << CI->arg_size() - 1;
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Sizes << ':';
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for (unsigned ArgCount = 1;
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ArgCount < CI->arg_size() && ArgCount <= OpConvSpecifiers.size();
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ArgCount++) {
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Value *Arg = CI->getArgOperand(ArgCount);
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Type *ArgType = Arg->getType();
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unsigned ArgSize = TD->getTypeAllocSize(ArgType);
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//
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// ArgSize by design should be a multiple of DWORD_ALIGN,
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// expand the arguments that do not follow this rule.
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//
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if (ArgSize % DWORD_ALIGN != 0) {
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Type *ResType = Type::getInt32Ty(Ctx);
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if (auto *VecType = dyn_cast<VectorType>(ArgType))
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ResType = VectorType::get(ResType, VecType->getElementCount());
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Builder.SetInsertPoint(CI);
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Builder.SetCurrentDebugLocation(CI->getDebugLoc());
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if (ArgType->isFloatingPointTy()) {
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Arg = Builder.CreateBitCast(
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Arg,
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IntegerType::getIntNTy(Ctx, ArgType->getPrimitiveSizeInBits()));
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}
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if (OpConvSpecifiers[ArgCount - 1] == 'x' ||
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OpConvSpecifiers[ArgCount - 1] == 'X' ||
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OpConvSpecifiers[ArgCount - 1] == 'u' ||
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OpConvSpecifiers[ArgCount - 1] == 'o')
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Arg = Builder.CreateZExt(Arg, ResType);
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else
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Arg = Builder.CreateSExt(Arg, ResType);
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ArgType = Arg->getType();
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ArgSize = TD->getTypeAllocSize(ArgType);
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CI->setOperand(ArgCount, Arg);
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}
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if (OpConvSpecifiers[ArgCount - 1] == 'f') {
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ConstantFP *FpCons = dyn_cast<ConstantFP>(Arg);
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if (FpCons)
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ArgSize = 4;
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else {
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FPExtInst *FpExt = dyn_cast<FPExtInst>(Arg);
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if (FpExt && FpExt->getType()->isDoubleTy() &&
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FpExt->getOperand(0)->getType()->isFloatTy())
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ArgSize = 4;
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}
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}
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if (shouldPrintAsStr(OpConvSpecifiers[ArgCount - 1], ArgType))
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ArgSize = alignTo(getAsConstantStr(Arg).size() + 1, 4);
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LLVM_DEBUG(dbgs() << "Printf ArgSize (in buffer) = " << ArgSize
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<< " for type: " << *ArgType << '\n');
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Sizes << ArgSize << ':';
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Sum += ArgSize;
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}
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LLVM_DEBUG(dbgs() << "Printf format string in source = " << FormatStr
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<< '\n');
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for (char C : FormatStr) {
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// Rest of the C escape sequences (e.g. \') are handled correctly
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// by the MDParser
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switch (C) {
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case '\a':
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Sizes << "\\a";
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break;
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case '\b':
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Sizes << "\\b";
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break;
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case '\f':
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Sizes << "\\f";
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break;
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case '\n':
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Sizes << "\\n";
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break;
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case '\r':
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Sizes << "\\r";
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break;
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case '\v':
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Sizes << "\\v";
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break;
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case ':':
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// ':' cannot be scanned by Flex, as it is defined as a delimiter
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// Replace it with it's octal representation \72
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Sizes << "\\72";
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break;
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default:
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Sizes << C;
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break;
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}
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}
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// Insert the printf_alloc call
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Builder.SetInsertPoint(CI);
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Builder.SetCurrentDebugLocation(CI->getDebugLoc());
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AttributeList Attr = AttributeList::get(Ctx, AttributeList::FunctionIndex,
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Attribute::NoUnwind);
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Type *SizetTy = Type::getInt32Ty(Ctx);
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Type *Tys_alloc[1] = {SizetTy};
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Type *I8Ty = Type::getInt8Ty(Ctx);
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Type *I8Ptr = PointerType::get(I8Ty, 1);
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FunctionType *FTy_alloc = FunctionType::get(I8Ptr, Tys_alloc, false);
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FunctionCallee PrintfAllocFn =
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M.getOrInsertFunction(StringRef("__printf_alloc"), FTy_alloc, Attr);
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LLVM_DEBUG(dbgs() << "Printf metadata = " << Sizes.str() << '\n');
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std::string fmtstr = itostr(++UniqID) + ":" + Sizes.str();
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MDString *fmtStrArray = MDString::get(Ctx, fmtstr);
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MDNode *myMD = MDNode::get(Ctx, fmtStrArray);
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metaD->addOperand(myMD);
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Value *sumC = ConstantInt::get(SizetTy, Sum, false);
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SmallVector<Value *, 1> alloc_args;
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alloc_args.push_back(sumC);
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CallInst *pcall =
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CallInst::Create(PrintfAllocFn, alloc_args, "printf_alloc_fn", CI);
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//
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// Insert code to split basicblock with a
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// piece of hammock code.
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// basicblock splits after buffer overflow check
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//
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ConstantPointerNull *zeroIntPtr =
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ConstantPointerNull::get(PointerType::get(I8Ty, 1));
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auto *cmp = cast<ICmpInst>(Builder.CreateICmpNE(pcall, zeroIntPtr, ""));
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if (!CI->use_empty()) {
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Value *result =
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Builder.CreateSExt(Builder.CreateNot(cmp), I32Ty, "printf_res");
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CI->replaceAllUsesWith(result);
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}
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SplitBlock(CI->getParent(), cmp);
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Instruction *Brnch =
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SplitBlockAndInsertIfThen(cmp, cmp->getNextNode(), false);
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Builder.SetInsertPoint(Brnch);
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// store unique printf id in the buffer
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//
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GetElementPtrInst *BufferIdx = GetElementPtrInst::Create(
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I8Ty, pcall, ConstantInt::get(Ctx, APInt(32, 0)), "PrintBuffID", Brnch);
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Type *idPointer = PointerType::get(I32Ty, AMDGPUAS::GLOBAL_ADDRESS);
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Value *id_gep_cast =
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new BitCastInst(BufferIdx, idPointer, "PrintBuffIdCast", Brnch);
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new StoreInst(ConstantInt::get(I32Ty, UniqID), id_gep_cast, Brnch);
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// 1st 4 bytes hold the printf_id
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// the following GEP is the buffer pointer
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BufferIdx = GetElementPtrInst::Create(I8Ty, pcall,
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ConstantInt::get(Ctx, APInt(32, 4)),
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"PrintBuffGep", Brnch);
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Type *Int32Ty = Type::getInt32Ty(Ctx);
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for (unsigned ArgCount = 1;
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ArgCount < CI->arg_size() && ArgCount <= OpConvSpecifiers.size();
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ArgCount++) {
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Value *Arg = CI->getArgOperand(ArgCount);
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Type *ArgType = Arg->getType();
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SmallVector<Value *, 32> WhatToStore;
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if (ArgType->isFPOrFPVectorTy() && !isa<VectorType>(ArgType)) {
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if (OpConvSpecifiers[ArgCount - 1] == 'f') {
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if (auto *FpCons = dyn_cast<ConstantFP>(Arg)) {
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APFloat Val(FpCons->getValueAPF());
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bool Lost = false;
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Val.convert(APFloat::IEEEsingle(), APFloat::rmNearestTiesToEven,
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&Lost);
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Arg = ConstantFP::get(Ctx, Val);
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} else if (auto *FpExt = dyn_cast<FPExtInst>(Arg)) {
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if (FpExt->getType()->isDoubleTy() &&
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FpExt->getOperand(0)->getType()->isFloatTy()) {
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Arg = FpExt->getOperand(0);
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}
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}
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}
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WhatToStore.push_back(Arg);
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} else if (isa<PointerType>(ArgType)) {
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if (shouldPrintAsStr(OpConvSpecifiers[ArgCount - 1], ArgType)) {
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StringRef S = getAsConstantStr(Arg);
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if (!S.empty()) {
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const uint64_t ReadSize = 4;
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DataExtractor Extractor(S, /*IsLittleEndian=*/true, 8);
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DataExtractor::Cursor Offset(0);
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while (Offset && Offset.tell() < S.size()) {
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uint64_t ReadNow = std::min(ReadSize, S.size() - Offset.tell());
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uint64_t ReadBytes = 0;
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switch (ReadNow) {
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default: llvm_unreachable("min(4, X) > 4?");
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case 1:
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ReadBytes = Extractor.getU8(Offset);
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break;
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case 2:
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ReadBytes = Extractor.getU16(Offset);
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break;
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case 3:
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ReadBytes = Extractor.getU24(Offset);
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break;
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case 4:
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ReadBytes = Extractor.getU32(Offset);
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break;
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}
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cantFail(Offset.takeError(),
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"failed to read bytes from constant array");
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APInt IntVal(8 * ReadSize, ReadBytes);
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// TODO: Should not bothering aligning up.
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if (ReadNow < ReadSize)
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IntVal = IntVal.zext(8 * ReadSize);
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Type *IntTy = Type::getIntNTy(Ctx, IntVal.getBitWidth());
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WhatToStore.push_back(ConstantInt::get(IntTy, IntVal));
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}
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} else {
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// Empty string, give a hint to RT it is no NULL
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Value *ANumV = ConstantInt::get(Int32Ty, 0xFFFFFF00, false);
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WhatToStore.push_back(ANumV);
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}
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} else {
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WhatToStore.push_back(Arg);
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}
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} else {
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WhatToStore.push_back(Arg);
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}
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for (unsigned I = 0, E = WhatToStore.size(); I != E; ++I) {
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Value *TheBtCast = WhatToStore[I];
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unsigned ArgSize = TD->getTypeAllocSize(TheBtCast->getType());
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StoreInst *StBuff = new StoreInst(TheBtCast, BufferIdx, Brnch);
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LLVM_DEBUG(dbgs() << "inserting store to printf buffer:\n"
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<< *StBuff << '\n');
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(void)StBuff;
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if (I + 1 == E && ArgCount + 1 == CI->arg_size())
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break;
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BufferIdx = GetElementPtrInst::Create(
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I8Ty, BufferIdx, {ConstantInt::get(I32Ty, ArgSize)},
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"PrintBuffNextPtr", Brnch);
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LLVM_DEBUG(dbgs() << "inserting gep to the printf buffer:\n"
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<< *BufferIdx << '\n');
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}
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}
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}
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// erase the printf calls
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for (auto *CI : Printfs)
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CI->eraseFromParent();
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Printfs.clear();
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return true;
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}
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bool AMDGPUPrintfRuntimeBindingImpl::run(Module &M) {
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Triple TT(M.getTargetTriple());
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if (TT.getArch() == Triple::r600)
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return false;
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auto PrintfFunction = M.getFunction("printf");
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if (!PrintfFunction || !PrintfFunction->isDeclaration())
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return false;
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for (auto &U : PrintfFunction->uses()) {
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if (auto *CI = dyn_cast<CallInst>(U.getUser())) {
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if (CI->isCallee(&U) && !CI->isNoBuiltin())
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Printfs.push_back(CI);
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}
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}
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if (Printfs.empty())
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return false;
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TD = &M.getDataLayout();
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return lowerPrintfForGpu(M);
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}
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bool AMDGPUPrintfRuntimeBinding::runOnModule(Module &M) {
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return AMDGPUPrintfRuntimeBindingImpl().run(M);
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}
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PreservedAnalyses
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AMDGPUPrintfRuntimeBindingPass::run(Module &M, ModuleAnalysisManager &AM) {
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bool Changed = AMDGPUPrintfRuntimeBindingImpl().run(M);
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return Changed ? PreservedAnalyses::none() : PreservedAnalyses::all();
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}
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